I use hnreplies and quite like it. Another option is
https://hnrss.github.io/#reply-feeds which gives you a feed of replies to a user (quite possibly yourself). The RSS option is of course more flexible because you can do whatever you want with the feed but I just read my RSS via email anyways so I just use hnreplies. IIUC it is also faster because it is polling for everyone quite frequently whereas individually polling the RSS feed I would probably do it at a lower interval.